Description (adapted from application): This laboratory was established in 1977 to provide radioimmunoassays to Center Investigators. Additionally, the Core characterizes secretory physiology of islets and cell lines (e.g. beta-TC, GH3) so that investigators can correlate secretory physiology with biochemical and molecular studies. The following services, provided by this Core in the current project period, will be continued in the proposed renewal of this Core: (A) RIA of insulin; (B) 125I-insulin; (C) cyclic AMP; (D) RIA of glucagon; (E) RIA of somatostatin and its propeptide; (F) RIA of rat growth hormone; (G) Plasma catechols; (H) Leptin levels; and (I) glucose determination.